I. Field
The present disclosure relates generally to electronics, and more specifically to a power amplifier and an output matching circuit.
II. Background
Amplifiers are commonly used in various electronic devices to provide signal amplification. Different types of amplifiers are available for different uses. For example, a wireless communication device such as a cellular phone may include a transmitter and a receiver for bi-directional communication. The transmitter may utilize a power amplifier (PA), the receiver may utilize a low noise amplifier (LNA), and the transmitter and receiver may utilize variable gain amplifiers (VGAs).
A power amplifier is an amplifier that can provide high output power for a signal to be transmitted. A power amplifier typically uses a matching network to translate a target impedance (e.g., 50 Ohms) at an antenna to a different impedance (e.g., 4 Ohms) at the power amplifier output. The matching network is typically fixed and hence presents the power amplifier with a fixed impedance or load line. The fixed impedance may be selected for maximum output power or high efficiency for the power amplifier. The fixed impedance may result in good performance for the power amplifier in operating scenarios for which the impedance is selected but may result in sub-optimal performance in other operating scenarios.